#include <stdio.h>
#include <string.h>
 float a,b,c;
void fun1()
{
      scanf("%f%f",&a,&b);
    c=a+b;
}
void fun2()
{
       scanf("%f%f",&a,&b);
        c=a-b;
}
void fun3()
{
   scanf("%f%f",&a,&b);
        c=a*b;
}
void fun4()
{
    scanf("%f%f",&a,&b);
        c=a/b;
}
int main()
{
    int num;

printf("************1-jia***************\n");
printf("************2-jian***************\n");
printf("************3-cheng***************\n");
printf("************4-chu***************\n");

while(1)
{
    printf("please chose\n");
  scanf("%d",&num);




switch(num)
{
case 1:
    {
        fun1();
    }
    break;
    case 2:
    {
        fun2();
    }
    break;
    case 3:
    {
        fun3();
    }
    break;
    case 4:
    {
        fun4();
    }
    break;
    default: printf("error please again!\n");
    break;
}
        printf("c=%f",c);
}

return 0;
}

